Reality about consumers’ ‘proper size’ portions of high-calorie food

13 June, 2022 | Vaishali Sharma


The outcomes of the study were published in the journal 'American Journal of Clinical Nutrition.' The findings, led by the University of Bristol, call into question the long-held belief that indivi...

According to new research, individuals limit the quantity of energy-dense meals they consume, implying that people are smarter eaters than previously assumed.

The outcomes of the study were published in the journal ‘American Journal of Clinical Nutrition.’ The findings, led by the University of Bristol, call into question the long-held belief that individuals are unconcerned with the energy content of the foods they eat and, as a result, consume the same amount of food (in weight) whether it is energy-rich or energy-poor.

The study, published today in The American Journal of Clinical Nutrition, is particularly intriguing since it defies a generally held view among experts that people are prone to overconsumption of high-energy meals.

Previous research has modified the energy content of foods or meals to generate low- and high-energy variants. People in those experiments were not told whether they were eating a low- or high-energy version, and the results revealed that they tended to eat meals of the same weight, resulting in higher calorie consumption with the high-energy version.

“For years, we assumed that humans blindly overeat energy-dense foods. Surprisingly, this study demonstrates a level of nutritional intelligence in which individuals can modify the quantity of high-energy-density foods they consume “Annika Flynn, a Doctoral Researcher in Nutrition and Behaviour at the University of Bristol, is the study’s principal author.

Rather than adjusting the calories in particular items, this study examined data from a trial including a regular, everyday meal with varying energy densities, such as a chicken salad sandwich with fig roll biscuits or oatmeal with blueberries and almonds. The research included 20 healthy people who were temporarily housed in a hospital ward and fed a variety of meals for four weeks.

The team of worldwide researchers analysed the calories, grammes, and energy density (calories per gramme) for each meal each participant ingested, including prominent specialists in food and metabolism from the National Institutes of Health (NIH) in the United States. The findings showed that meal calorie intake increased with energy density in energy-poor meals, as previously shown with experimentally manipulated meals also found.

Surprisingly, when energy density increased, a tipping point was discovered where people began to respond to increases in calories by lowering the amount of the meals they consumed. This shows a hitherto unknown sensitivity to the energy composition of the meals consumed.

Because this discovery was based on data from a short, well-controlled study, the researchers investigated if this trend persisted when individuals lived independently and chose their own meals.

Using data from the UK National Diet and Nutrition Survey, researchers discovered that meal calorie consumption rose with energy density in low-energy meals and dropped in high-energy meals. Importantly, in order for this turning point pattern to occur, participants would have required to consume lower portions of the more energy-rich meals.

“For example, participants ate smaller quantities of a creamy cheese pasta dish, which is an energy-rich meal, than a salad with a variety of veggies, which is relatively energy-poor,” Annika explained.

This study gives fresh information on human eating habits, notably an apparent slight sensitivity to calories in high-energy meals.

“This research adds weight to the hypothesis that people aren’t passive overeaters after all, but exhibit the discriminating capacity to limit how much of an energy-rich meal they take,” said co-author Jeff Brunstrom, Professor of Experimental Psychology.

“This discovery is especially fascinating because it uncovers a hidden complexity in how people engage with current energy-rich meals, which we’ve dubbed ‘nutritional intelligence.’ This indicates that humans do not appear to passively overconsume certain foods, and hence the rationale for their association with obesity is more complicated than previously imagined. For the time being, this provides a fresh viewpoint on an old problem and opens the door to a slew of new issues and paths for future investigation.”